This invention relates to sealing assemblies for use in sealing between cylindrical surfaces and has particular application to situations where seals are required to carry out a sealing function after they have undergone some rotation. The present sealing assembly has been designed particularly for use in subsea equipment, but its application is by no means limited to that application.
In subsea drilling equipment resilient sealing assemblies are often required at some stage during installation of the equipment to undergo rotation and then subsequently carry out an effective sealing function. An example of this requirement arises with what is known as an external tieback connector which is used to connect tieback equipment to a subsea wellhead assembly. The tieback connector includes a rotatable sleeve which is used to drive an external ring to actuate locking dogs for connecting the tieback connector to the wellhead housing. Seals are provided between the rotatable sleeve and the body of the tieback connector and these seals need to carry out an effective sealing function, both before and after rotation of the sleeve. Typically the seals need to be able to seal against pressures of the order of 10,000 psi. It has been customary to provide resilient seals of the "O" ring or lip seal type, but there have been problems in providing seals which can meet the requirement referred to above. The present invention is concerned with a sealing assembly which has been designed in order to at least alleviate these problems.